Phytochemical analysis and Gene expression profiling of Tribulus terrestris L and Pedalium murex L

Abstract

Tribulus terrestris L. and Pedalium murex L., are one of the most significant annual medicinal herbs valued for its steroidal saponins, especially diosgenin . Both herbs parts have been used as traditional medicine to treat sexual dysfunctions, cough, asthma, and diuretic, etc. and are classified into numerous types of secondary metabolites namely, steroidal saponins, alkaloids, flavonoids, vitamins, and potassium, etc. Amongst them, steroidal saponins are present in highest amount; the key component being diosgenin. Despite, diosgenin biosynthesis pathway is not understood in both the herbs. In the present study, quantification of diosgenin content in roots, leaves, stems, and fruits was done through LC-MS. The highest amount of diosgenin content was observed in T. terrestris root and P. murex fruit (2.98 and 1.63 µg/mg), respectively. To define the transcriptome profile, RNA of root, leaf, and fruit of T. terrestris and P. murex were pooled and converted to cDNA and sequencing was done using the Illumina Hiseq2000 platform, in which ~7.9 and ~6.77 GB raw nucleotide data were generated respectively. Comparative analysis showed that 691 and 100 genes were significantly up-regulated and down-regulated, respectively. In de novo assembly of both herb a total of 112182 and 75198 numbers of respective transcript contigs were analyzed. Putative functions could be annotated to 200471 and 148871 unigenes based on BLASTX search against the NR, Uniprot, KEGG, Pfam, GO, and COG database. Transcriptome data from T. terrestris and P. murex revealed gene families involved in the biosynthesis of diosgenin. To confirm differential expression of the identified genes qRT-PCR was done. Moreover, most of the genes are similar in heat map except for 15 and 22 genes, which are highly down and up regulated in T. terrestris and P. murex, respectively. T. terrestris and P. murex showed the highest homology with Quercus suber and Sesamum indicum, respectively. In transcription factor families, a total of 27477 and 21026 unigenes of TFs were constructed. A total of 17623 and 8760 SSRs unigenes were collected from both plants. These data will facilitate our understanding of diosgenin biosynthesis pathway and further serve as an important public information platform for gene mining, molecular breeding, and functional genomic studies. newline